UMC claims 28-nm SRAMs

UMC uses double-patterning immersion lithography and advanced strained-silicon technology for the 28-nm chips.

By Suzanne Deffree, Managing Editor, News -- Electronic News, 10/27/2008

UMC today claimed to have manufactured fully functional 28-nm SRAM chips based on its low-leakage process technology.

The foundry used advanced double-patterning immersion lithography and strained silicon technology to produce the chips, which feature six-transistor SRAM cell sizes of approximately 0.122-squared microns.

UMC's announcement follows on plans from IBM and its Common Platform Alliance partners Chartered and Samsung that will see their joint work treat 32 nm and 22 nm as standard nodes, and 28 as a half node.

UMC's announcement also comes approximately one month after TSMC, the company's main rival and the foundry market leader, disclosed early information on its planned 28-nm process node work. That work will in effect divided TSMC's move to 28 nm into two separate tracks: one that stays with a conventional silicon-oxy-nitride gate technology and an enhanced version of conventional strain engineering, and a higher-risk approach that uses a high-k/metal-gate stack.

Like its rival, UMC incorporates a dual approach for its 28-nm technology to address different market applications. The foundry uses conventional silicon gate/silicon-oxy-nitride gate oxide technology for its low-leakage process, which it claims is ideal for portable applications such as mobile phone ICs. UMC’s second option will use a high-k/metal gate stack for speed-intensive products such as graphic, application processor, and high-speed communication ICs.

According to the UMC, its 28-nm process provides almost twice the density of its 40-nm technology, which is currently being produced at its 300-mm fabs.

UMC further said it will provide foundry services for customized 32-nm technologies based on its 28-nm process platform.

“We are excited about this latest achievement for 28 nm, as it provides a solid starting point for further development of this technology node towards mainstream availability down the road," said SC Chien, VP of advanced technology development at UMC, in a statement. "Improvements on areas such as minimum supply-voltage, modeling of strain effects, and natural yield will be our focus going forward.”